Optical supersensitisation of silver halide emulsions with three cyanine dyes

ABSTRACT

THIS INVENTION RELATES TO PHOTOGRAPHIC LIGHT-SENSITIVE MATERIAL WHICH COMPRISES A SILVER HALIDE EMULSION CONTAINING A SUPER-SENSITIZING COMBINATION. THE LATTER CONSISTS OF THREE DIFFERENT DYESTUFFS. IT IS USEFUL FOR INCREASING THE SENSITIVITY OF A GREEN SENSITISED EMULSION.

Ami 24, 1W3 RJEFFERSON ET AL 3,729,319

OPTICAL SUPERSENSITISATION OF SILVER HALIDE EMULSIONS WITH THREE CYANINE DYES Filed June 2, 1971 8m 2 on Q2 o c+5+- as $536 NQI gas 89m? 02 v 5 8m @Q o; /r.

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'amodxg 50 941101221 amsodxg 5o QA UUIQZj ROBIN JEFFERSON and CHRISTOPHER JOHN PALLES,

Inventors Attorneys United States Patent Int. Cl. G03c 1/14 US. Cl. 96124 4 Claims ABSTRACT OF THE DISCLOSURE This invention relates to photographic light-sensitive material which comprises a silver halide emulsion containing a super-sensitizing combination. The latter consists of three different dyestuffs. It is useful for increasing the sensitivity of a green sensitised emulsion.

Photographic silver halide emulsions have a certain natural sensitivity to light, but this is restricted to a short range of wavelengths in the ultra-violet and/or blue regions of the spectrum. The elfect of incorporating a sensitising dye is to impart to the emulsion sensitivity to light of other wavelengths. It has been known forsome years that by incorporating in the emulsion, together with the sensitising dye, a second substance or a second and third substance which may or may not themselves be sensitising dyes, there may sometimes be imparted to the emulsion an additional sensitivity beyond that which can be regarded as the sum effect of the separate substances. Combinations of sensitising dye and other substances which give this better result are known as super-sensitising combinations.

The present invention is based on the discovery of a new super-sensitising combination of the type just referred to.

According to the present there is provided a photographic silver halide emulsion which comprises a supersensitising combination which consists of a sensitising dye of the general Formula I:

wherein R and R are hydrogen atoms or methyl groups, R is a snlphoalkyl or carboxyalkyl group, R is a lower alkyl group and X is an anion, or the corresponding zwitterion formed by the elimination of the anion X and the hydrogen atom of the sulphonic acid group together with a sensitising dye of the general Formula II:

wherein R is a carboxyalkyl or sulphoalkyl group, R is a methyl or ethyl group and R is a lower alkyl group and X is an anion, or the corresponding zwitterion formed by 3,729,319 Patented Apr. 24, 1973 the elimination of the anion X and the hydrogen atom of the snlphonic acid together with a sensitising dye of the general Formula HI:

wherein R is an alkyl or substituted alkyl group or the corresponding zwitterion formed by the elimination of the anion X and the hydrogen atom of the sulphonic acid when R is a snlphoalkyl group.

By lower alkyl group is meant an alkyl group containing from 1 to 4 carbon atoms.

Examples of suitable substituted alkyl groups of R are alkoxyalkyl, carboxyalkyl and sulphoalkyl.

From 0.01 g. to 0.3 g. of each sensitising dye per 1.5 g. mols of silver present in the emulsion can be conveniently used.

By use of a combination of dyes as just set forth a valuable eifect is obtained and is illustrated by the specific examples which are set forth later herein. The supersensitising combination as hereinbefore set forth finds particular use in increasing the sensitivity of a greensensitised emulsion. Dyes of Formula I, II and HI are in general green sensitisers and when a combination of these dyes is used in an emulsion an enhancement of the green sensitivity is obtained over the green sensitivity due to any one dye alone or due to a combination of any two of the three dyes. Moreover, the red speed of the dye of Formula II is considerably reduced in the combination. This is of value in colour photographic material because the green sensitive layer is required to have as low a red sensitivity as possible.

The super-sensitising combination of dyes as just set forth is of particular use in that form of colour photographic material where the emulsion comprises substantive colour couplers because, in general, the dyes used in the super-sensitising combination are resistant to the desensitising action of substantive colour couplers.

Furthermore, when the combination of all three dyes is present, the emulsion which contains the dyes is found to have improved storage properties both before exposure and after exposure.

The following examples will serve to illustrate the invention:

EXAMPLE 1 The following dyes were used:

Dye A, which is a dye of Formula I had the following formula:

CCH I Dye B which is a dye of Formula II had the following formula:

4 In Table 2 which follows the amount in g. per 1 /2 moles of silver halide of each of the dyes A B and C contained in each strip is indicated by the figures on the S left hand columns. The figures in the Fog Change" CH3 5 column show the difference between the control strips C-GH= JCH=O fog and the incubated strips fog in one column and between the, control strips fog (Inc.) and the strips which N N were subjected to the accelerated latent image process (43m): (B2115 in the other column (A.L.I.). Similarly different figures are shown for the Log Speed Change and Contrast 503 Change.

TABLE 2 Fog change Log speed change Contrast change Incuba- Incuba- Incubation, A.L.I. Dye Ar Dye C1 Dye B1 tion A.L.I. tion A.L.I. percent percent .35 +.02 .02 .02 .05 5 14 .35 +.01 0 $.04 0 t; in .35 01 01 0 02 -1 +28 .25 .25 01 02 +.01 01 +6 .10 .10 0 +.02 10 -.01 +4 +6 .15 .075 0 0 +.04 -.01 -5 +1 .075 .075 02 01 02 +03 4 +4 .075 .15 0 +.02 +.04 05 -4 +4 Dye C which is a dye of Formula 111 had the following From Table 2 it may be seen that changes which have formula: occurred in the fog and in the log speed of the emulsions 0 0 due to both the incubation and the accelerated latent C2115 image tests are of the same order for both the dyes alone Q 35 and in combination. For changes in contrast however, emulsion which contains the three dyes shows an im- 1; provement, especially on the accelerated latent image 8 test. Changes in contrast must be minimised in order (hHOGH to maintain correct colour balance of integral tripack lour materials during storage. The dyes were adoeu as shown in Table l, to portions c0 of a high speed silver iodobromide emulsion containing T presepce of the magenta coupler had very hale 5 4 mol percent of silver iodide after digestion of the smppmg action on any of the dyes as Show?! by the fact that on coating the dyes or d e mixture whlch had stood emulsion the quantity shown for each dye being the y amount per 1 /2 g. mols of silver halide. Each portion was m i prefsence 3 magenta colour coupler for three hours coated onto film strip. After exposure through a conno 085 0 Spee was observed tinuous wedge the strips were developed and the rela- TABLE 3 tive log speed of the emulsions were determined. The Speeds are relative spfieds measured to light Passing Dyes contained in emulsion: Relative speed loss through a yellow filter, the term relative 10g speed being B1, and c 5 directly related to the logarithm of the reciprocal of the A1 00 exposure in metre-candle-seconds required to produce a C1 0Q dcnsty of 0.1 above fog. A higher figure indicates a higher 13 spee TABLE 1 The reduction in the red speed of dye B when in Relative combination with dyes A and C is shown in the accom- Dye A Dye C! Dye Bl 10g speed panying drawings. Graph 1 (FIG. 1) shows the wedge 030 3 37 spectrogram of dye B alone. This shows the large area "5351:1111: 3:60 of sensitivity beyond 580 nm. The area 580 to 600 nm.

8.2g 3g is very critical from the point of view of colour reproducj tion, this being the area of overlap between the red and 0-075 green sensitive layers. It is preferred that there is some In order to demonstrate the improved storage prop Sensitivity up to 59Ohbut 1 degree (ugly. 2-FIG.2 owsteweesectro amoa erties of emulsions comprising the combination of all 65 $25 1 dyes 3 and s shgws g the area of 69% relative humidity. After incubation they were ex- In EXamP1?S T whlch c i the f fil EY Smglg posed and processed together with similar strips which f combma'tlon were. ad ed to a slml 1g P had been stored for one week at 10 C. and 50% relative sllvel fodobromlde emulslon as used 111 Example T e humidity. An accelerated latent image test was also 70 6111111510115 50 P twere exPosed, P and carried out in which uneXpOsed film strips as just preevaluated as set forth in Example 1. The incubation tests pared were exposed and then stored for one week at were also carried out as described in Example 1. 43 C. and 69% relative humidity. These strips were The amount of dyes used in the emulsion are shown in processed together with the above strips which were exthe tables as g. per 1%. g. moles of silver halide in the posed just prior to processing. emulsl 5 6 EXAMPLE 2 Dye C which is a dye of Formula III had the follow- The following dyes were used: mg formula Dye A which is a dye of Formula I had the foliowing 0 formula /CCH=C-CH=O\ (52116 The results obtained are shown in Table 7. $11,000]; I- TABLE 7 Dye B of Example I. Relative log Dye C which is a dye of Formula III had the follow- Dye A! C3 Dye B3 speed ing formula 0.30 s. 17 0.30 5.50 an.

E a The presence of magenta coupler had very little stripping action shown in Table 8.

The results obtained are shown in Table 4.

TABLE 4 TABLE 8 Dye A1 Dye G1 Dye B Relative log Dyes contained in emulsions: Relative speed loss speed A2 B8 C3 00 0.30 A -.03 "a a 3"?? l f l 2 8; 015 I15 3152 3 0075 0.15 0 075 3. 03 Incubatlon test results are shown in Table 9.

TABLE 9.INCUBA'IION TEsT REsULTs Fog Log speed change Contrast change In uh I b lnctl'lba' A L I c an u an, Dye A: Dye C5 Dye Ba tion A.L.I. tion A.L.I. per nt percent The presence of magenta coupler had very little EXAMPLE 4 stripping action as is shown in Table 5. The f ll i dyes were used;

Dye A which is a dye of Formula I had the following TABLE 5 formula Dyes contained in emulsion: Relative speed loss 5 CH3 A B, 0: 00 COH=C N B 00 (IJZH5 The incubation test results are shown in Table 6 (K JHmSOr TABLE 6.INCUBATION TEsT RESULTS Fog change Log speed change Contrast change Incuba- Incuba- Incubation, ALL, Dye A: Dye B Dye C1 tion A.L.I. tion A.L.I. percent percent EXAMPLE 3 Dye B; which is a dye of Formula II had the following The following dyes were used: formula Dye A of Example 2 Dye B which is a dye of Formula II had the following formula S 0 s C o CrHs 0-CH- -CH--C 5 i 5 5 (onmoonz 02H, H3

7 Dye C which is a dye of Formula III had the following presence of a sulfonic acid group in the radical R formula and is 2 in the case of a non-betaine-like molecular o structure, 02H; (2) a sensitising dyestufi of the formula /C-CH= -OH=G\ 5 s\ R o i N C-CH=(J-CH-C/ I (bmnooi- ((JHzhCOzM g/ \N (Yeh-r The results obtained are shown in Table 10. 1h, 1'1.

TABLE 10 wherein R represents a carboxyalkyl group or a sul- Relative phoalkyl, R represents a methyl or ethyl group, R Dye A Dye B Dye C ggg represents a lower alkyl group, represents an amon, and q is 1 in the case of a betame-like molecu- :55-3: 3: gig lar structure caused by the presence of a sulphonic 0.30 3.54 acid group in the radical R and is 2 in the case of M5 3; 33;: a non-betaine-like molecular structure, and 0.075 0.15 0. 075 3.58 (3) a symmetrical bis-benzoxazole sensitising dyestuff of the formula 2 l C-CH=7-CH=C (Z b-i N t, in

The presence of magenta couplers had very little wherein R represents a member selected from the Stnppmg acnon as g l dg fl group consisting of an alkyl group, an alkoxyalkyl Dyes contained in group, a carboxyalkyl group and a sulphoalkyl group, emulsions: R l ti speed1oss Z represents an anion and r is 1 in the case of a 4+ 4+ 4 betaine-like molecular structure caused by the pres- 3: i' ence of a sulphonic acid group or a carboxylic acid C4 7 group in the radical R and r is 2 in the case of a The incubation tests results are shown in Table 12. non-betaine-like molecular structure.

TABLE 12.INOUBATION TEST RESULTS Fog change Log speed change Contrast change Incuba- Incuba- Ineubar tlon, A.L.I., Dye A4 Dye C4 Dye Bl tion A.L.I. tion A.L.I. percent percent 0.3 +.01 o -.11 +.10 -12 +3 0. 3 o o 17 05 -e 0. a 0 0 07 01 -7 +19 0.15 0 15 +.01 01 02 0 +4 +46 0.075 0.15 0.076 +.01 +.01 -.02 -.o3 --4 +27 From Tables 6, 9 and 12 it may be seen that changes which have occurred in the fog and in the log speed of the emulsions due to both the incubation and the accelerated latent image tests are improved when the three dye combination is present.

We claim:

1. A photographic silver halide emulsion which contains a super-sensitising combination which comprises (1) a sensitising dyestutf of the formula U O CH n, g/

wherein R and R each represents a member selected from the group consisting of a hydrogen atom and a methyl group, R2 represents a sulphoalkyl group or a carboxyalkyl group, R represents a lower alkyl group, X represents an anion and p is 1 in the case of a betaine-lilge molecular structure Caused by the (It m 2. A photographic silver halide emulsion as claimed in claim 1 which comprises (1) a sensitising dyestuif of the formula (2) a sensitising dyestuff of the formula s 0 C-CH=CHOH=C r OZ u wherein s equals 1 or 2, (a) R represents each a member selected from the group consisting of an ethyl group and a ,B-methoxy ethyl group if s equals 2, and (b) R represents a member selected from the group consisting of a lower alkyl sulfonic acid group an a lower alkyl carboxylic acid group, the acid group of the radical R being bound to the quaternary nitrogen in a betaine-like molecular structure, if s equals 1.

3. A photographic emulsion as claimed in claim 1, which comprises 0.01 to 3 g. of each sensitising dyestufif per 1.5 gram equivalents of silver present in the emulsion.

4. A photographic emulsion as claimed in claim 1, which contains a magenta colour coupler.

References Cited UNITED STATES PATENTS J. TRAVIS BROWN, Primary Examiner US. Cl.

UNITED STATES PATENT GFFICE CERTIMCATE or c RECTEON Patent No. 3,729,319 Dated April 24 1973 Inventor('s) Robin Jefferson and Christopher John Palles It: is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Insert in the Heading of the Patent, after the Serial No.,

--Claims priority, application Great Britain, June 4, 1970,

Signed and sealed this 12th day of March 197A.

(SEAL) Attest:

C. MARSHALL DANN EDWARD M. FLETCHER, mo.

Commissioner of Patents Attesting Officer FORM po'mso HO'GS) I uscoMM-oc scan-P69 Y W U.. GOVERNMENT PRINTING OFFICE 7 19.50-35-33, y 

